In the prior art seat support structure of a bicycle, U.S. Pat. No. 7,025,367 discloses an adjustable air cushion bicycle seat hydraulic ram system mounted within the seat post of a bicycle frame, having: a. a hollow ram with one end attached to the bicycle seat and an open end, b. an internal bicycle frame reservoir with an open end secured to the seat post sized to accommodate the open end of the ram slideably sealed in the internal bicycle frame reservoir open end to create an enclosed pressurized liquid/air column within the internal bicycle frame reservoir, c. a valve with walls defining channels in communication and located between the internal bicycle frame reservoir wherein the thickness of the valve walls and size of the wall channels and the liquid are selected to provide hydraulic flow resistance to delay the response of the ram to rapid changes in the internal bicycle frame reservoir pressure to prevent abrupt extension or contraction of the ram mounted seat to shock to the rider, and d. an adjustable pressurized air/liquid reservoir having filling means to selectively fill the air/liquid reservoir such that the valve adjusts the height, volume, and pressure of the air and liquid columns within the internal bicycle frame reservoir to form a desired air cushion within the ram to provide the desired ride cushion.
The prior art seat support structure of a bicycle has complicated structures and contains a large amount of parts so that the cost is high and it is difficult to assembly and also difficult to adjust the elevation of the seat support structure. Thereby the tightness of the whole structure is not preferred.